The invention relates generally to apparatus and methods for delivery of a gas and more specifically to apparatus and methods for controlling the amount, rate and duration of gas delivery.
The use of gas for retarding, controlling, killing or preventing microbiological contamination (e.g., bacteria, fungi, viruses, mold spores, algae and protozoa); retarding, preventing, or controlling biochemical decomposition; controlling respiration, deodorizing and/or retarding and preventing chemotaxis to name a few, is known. Such gases include, but are not limited to, chlorine dioxide, sulfur dioxide, nitrogen dioxide, nitric oxide, nitrous oxide, carbon dioxide, hydrogen sulfide, hydrocyanic acid, and dichlorine monoxide. For example, the use and efficacy of chlorine dioxide is documented and discussed in various publications such as G. D. Simpson et al., A Focus on Chlorine Dioxide, An Ideal Biocide (visited Feb. 5, 2000) http://clo2.com/readings/waste/corrosion.html, and K. K. Krause, DDS et al., The Effectiveness of Chlorine Dioxide in the Barrier System (visited Feb. 5, 2000) http://www.dentallogic.com/dentist/effects.htm.
In particular, chlorine dioxide has been found to be useful as a disinfectant, antiseptic and sanitizer. It is used, e.g., to disinfect drinking water and various water supplies. In addition, chlorine dioxide finds use as a bleaching agent for flour, fats and textiles. Chlorine dioxide also has shown great utility as an antiseptic for treating metal and plastic surfaces, as well as other substrates such as countertops, meat processing and packaging equipment, and dental and medical instruments and devices.
One disadvantage of the prior art methods for generating chlorine dioxide gas generally is that unsatisfactory levels of by-products or reactants remain as a residue. For example, in the case of chlorine dioxide gas, the byproduct chlorite leaves residues on food handling equipment and medical and dental surfaces. Human contact with such residues should be avoided or substantially minimized according to FDA and EPA regulations.
Another requirement in the food handling and related industries is the need for raw materials or ingredients that are safe to handle in the preparation of the disinfectant. The requirement is for the inclusion of reagents that are safe to use and, after generating chlorine dioxide, produce side products that are non-toxic and/or biodegradable.
Also, although it has great beneficial characteristics, chlorine dioxide can not be transported commercially as a concentrated gas for its use and instead has been generated at the site where it is used. Thus, an on-site gas generation plant typically is required to generate the gas that is then delivered to the fluid in which it will be used. Such apparatus takes up space and represents a significant added expense. Moreover, even when prior art apparatus do not require a separate gas generation component e.g., those shown in European Patent Publication No. 0 571 228 for sulfur dioxide generation, such apparatus are still undesirable because controlling the amount of gas generated, the efficiency of the generation, and the duration of the gas generation has proven difficult, if not unsuccessful.
There exists a need for the controlled, on-site generation of gases, such as sulfur dioxide and chlorine dioxide, which can be produced safely, efficiently and economically, without the necessity for a separate generation plant or unwanted by-products. The present invention addresses these needs.
A novel approach to the delivery of gas has now been discovered. The present invention uses a unique delivery system that controls the rate and efficiency of gas-producing reactions. Moreover, by using discreet amounts of reactant contained within a multi-layered apparatus, the skilled practitioner can now fabricate a gas delivery apparatus that is compact, cost-effective and safe. Furthermore, the present invention can be used for a variety of applications, including delivery of gas to air or water, for a variety of purposes including disinfection, deodorization, bleaching and sanitization.
In one aspect, the present invention features an apparatus for delivery of a gas. An exemplary embodiment of this apparatus generally includes an envelope, a sachet disposed within the envelope, and a reactant disposed within the sachet that generates a gas in the presence of an initiating agent, wherein the envelope allows release of the gas from the envelope.
One currently preferred embodiment of the invention features an apparatus for delivery of a gas which includes a first reactant disposed within a first sachet, a second reactant disposed within a second sachet, a third sachet disposed about the first sachet and the second sachet, an envelope disposed about the third sachet, a frangible pouch disposed within the envelope adjacent to the third sachet, and an initiating agent disposed within the frangible pouch. In this embodiment, the first reactant and the second reactant generate a gas in the presence of the initiating agent, and the envelope allows release of the gas from the apparatus.
In a third exemplary embodiment, the apparatus for delivery of a gas includes an envelope, a partition disposed within the envelope defining a first volume and a second volume, a first reactant disposed in the first volume, and a second reactant disposed within the second volume. In this preferred embodiment, the first reactant and the second reactant generate a gas in the presence of an initiating agent, and the envelope allows entry of the initiating agent into the apparatus.
In another embodiment, the apparatus for delivery of a gas includes a sachet and a reactant disposed within the sachet that generates a gas in the presence of an initiating agent. In this embodiment, the sachet allows contact of the initiating agent with the reactant and release of the gas from the apparatus.
In another aspect, the present invention features a method of forming an apparatus for delivery of a gas including the steps of (a) providing a multi-layer structure comprising a reactant layer centrally disposed between two sachet layers, and two envelope layers disposed adjacent to the two sachet layers such that the two sachet layers are centrally disposed between the two envelope layers, and (b) stamping the multi-layer structure such that the two envelope layers form an envelope defined about its perimeter by the stamp, and the two sachet layers form a sachet defined about its perimeter by the stamp.
In yet another aspect, the present invention features a method of delivering gas including the steps of (a) providing an apparatus for delivery of a gas comprising: an envelope, a sachet disposed within the envelope, and a reactant disposed within the sachet that generates a gas in the presence of an initiating agent, wherein the envelope allows release of the gas from the envelope; and (b) disposing the apparatus in an environment that comprises an initiating agent. The environment can be liquid and the initiating agent can be water. Alternatively, the environment can be gaseous and the initiating agent can be water vapor.
In short, the invention provides the art with a heretofore unappreciated method and apparatus for the controlled generation of a gas. Moreover, in accordance with the present teachings, the invention can also readily be applied to the generation of a liquid.
The invention will be understood further upon consideration of the following drawings, description and claims.